Sensitivity to base-flow variation of a streamwise corner flow

The stability of flow formed by intersection of two perpendicular flatplates is revisited through a study of the sensitivity to the base flow variation. After a brief presentation of the asymptotic regime, sensitivity functions underlying corner mode (concentrated close to the intersection) and Tollmien-Schlichting modes, with different obliqueness angles, are computed. With this consideration, associated mechanisms as well as active regions are identified, which further confirm that the sensitivity area of the corner mode arises along the intersection of flat plates. Then, an optimization technique shows that a small deviation of the reference field in the area of uncertainty observed in experiments leads to decrease critical Reynolds number. A hypothesis based on the onset of an inflectional mechanism is thus proposed to explain the experimental results.